1. Field of the Invention
The present invention relates to an ink composition suitably used for inkjet recording, and an inkjet recording method employing the ink composition, a printed material and a process for producing a formed printed material.
2. Description of the Related Art
As image recording methods for forming an image on a recording medium such as paper based on an image data signal, there are an electrophotographic system, sublimation type and melt type thermal transfer systems, an inkjet system, etc. In the electrophotographic system, a process of forming an electrostatic latent image on a photosensitive drum by electrically charging and exposing is required, and the system is complicated; as a result, there is the problem that the production cost is high. With regard to the thermal transfer system, although the equipment is inexpensive, due to the use of an ink ribbon there is the problem that the running cost is high and waste material is generated.
On the other hand, with regard to the inkjet system, the printing equipment is inexpensive, it is not necessary to use a plate when printing, and since an image is formed directly on a recording medium by discharging an ink composition only on a required image area, the ink composition can be used efficiently and the running cost is low, particularly in the case of small lot production. Furthermore, there is little noise and it is excellent as an image recording system, and has been attracting attention in recent years.
Among them, an inkjet recording ink composition (radiation-curing inkjet recording ink composition), which is curable upon exposure to radiation such as UV rays, is an excellent system from the viewpoint of it being possible to print on various types of substrates because, compared with a solvent-based ink composition, the drying properties are excellent and an image is resistant to spreading since the majority of the components in the ink composition cure upon exposure to radiation such as UV rays.
Furthermore, the ink compositions below are known.
JP-PCT-2004-514014 (JP-PCT denotes a published Japanese translation of a PCT application) discloses an inkjettable radiation-curable inkjet ink composition comprising (a) an oligo/resin component; and (b) a radiation-curing reactive diluent comprising (i) 0.1 to 50 wt % of an adhesion-promoting radiation-curable component comprising one or more heterocyclic radiation-curable monomer and/or an alkoxylated monomer comprising pendant alkoxylated functionality and no main chain alkoxylated functionality, and (ii) no greater than about 10 wt % of an optionally alkoxylated radiation-curable monomer comprising main chain alkoxylated functionality.
JP-PCT-2004-518787 discloses a radiation-curing inkjettable ink composition comprising an oligomer that is a reaction product of components comprising (a) an aliphatic polyisocyanate comprising two or more isocyanate groups and (b) a radiation-curing alcohol comprising one or more radiation-curing moieties, one or more hydroxy moieties, and one or more polycaprolactone ester moieties.
JP-PCT-2004-536925 discloses an inkjet ink composition comprising a colorant, a vehicle, and a specific fluorochemical surfactant.
JP-A-2008-105393 discloses a process for producing a molded printed material comprising (A) a step of forming an image by discharging onto a support by an inkjet method an ink composition comprising, in the ink composition, at least 60 wt % of a monofunctional radically polymerizable monomer having only one unsaturated double bond group selected from the group consisting of an acrylate group, a methacrylate group, an acrylamide group, a methacrylamide group, and an N-vinyl group and at least one group having a cyclic structure, (B) a step of obtaining a printed material having an image cured on the support by irradiating the obtained image with actinic radiation so as to cure the ink composition, and (C) a step of molding the printed material.